Carton blanks and resulting cartons with fulcrum locking of side panels



United States Patent Ofi ice 3,226,06 Patented Dec. 28, 1965 3,226,006 CARTON BLANKS AND RESULTING CARTONS WITH FULCRUM LOCKING OF SIDE PANELS Maurice B. Dunn, Charlotte, N.C., assignor to Memco Machinery Corporation, Charlotte, N.C., a corporation of North Carolina Filed Nov. 27, 1962, Ser. No. 240,298 11 Claims. (Cl. 229-35) This invention relates to a foldable blank for forming cartons, such as containers or covers. It also relates to the resultant carton.

Paperboard or like type cartons are well-known, and are frequently employed in many different industries, for example to enclose bakery goods. The sort of carton which this invention contemplates may be so utilized, but limitation thereto is not intended since its use is obviously of greater potential. One of the disadvantages of prior art cartons, such as the box and box blank in FIGURES l and 2 of the Meller Patent No. 2,634,899, granted April 14, 1953, is that it cannot be erected or set up automatically by machinery, but instead requires manual operation to effect the complete locking of adjacent side panels. On the other hand, cartons such as that referred to in the Dunn Patent No. 3,029,712, granted April 17, 1962, which can be automatically erected by machines have the disadvantage of their adjacent side panels being too easily unlocked.

It is the object of this invention to overcome both of these prior art disadvantages so as to provide a carton blank which can, though it need not be, automatically set up by machinery into an erected operative position in which its adjacent side panels are positively locked and not capable of being inadvertently unlocked.

Originally disclosed and claimed herein, but now disclosed and claimed in my copending divisional application Serial No. 403,675 filed September 10, 1964 and entitled Method and Apparatus for Making Cartons from Blanks, are method and apparatus for setting up such a positive locking carton.

Other objects and advantages of this invention will become apparent to those of ordinary skill in the art upon reading the appended claims and the following detailed description of the invention in conjunction with the attached drawings, in which:

FIGURE 1 is a plan view of a flat carton blank embodying this invention, the inside surface of the blank facing the observer;

FIGURE 2 is a perspective view of a carton set up from the blank shown in FIGURE 1, left end interlocks being shown in half completed condition;

FIGURE 3 is an elevational front view of the lower left corner of FIGURE 2 as indicated by the line 33;

FIGURE 4 is the same view as FIGURE 3 but showing the flexing operation necessary to get the tab tip tucked in;

FIGURE 5 shows an inside view of the upper left corner of FIGURE 2 in cross-section and elevation during the tip tucking in operation; and

FIGURE 6 is the same view as FIGURE 3 except with the tab tip tucked into locked position.

FIGURES 7 and 8 of my aforesaid divisional application are respectively similar to FIGURES l and 2 of the above-mentioned Dunn Patent No. 3,029,712, with modifications necessary to effect erecting of the carton blank of FIGURE 1 herein into the carton of FIGURE 2. The modifications made to the machine in that Dunn patent are discussed in my' divisional application and reference may be made to that patent for any other details not set forth therein.

In the carton blank shown in FIGURE 1, the central area defined within hinge or fold lines 200, 202, 204 and 206 is the main or inside panel 208 of the carton, forming for example the bottom panel thereof. It must be appreciated however, that the carton while its main use may generally be as a container or box, may likewise be used as a cover or lid in which case the main panel 208 would become the top of the carton.

Hinged to the respective edges of main panel 208 are side panels 210, 212, 214 and 216. For convenience, the panels 212 and 216 are herein sometimes referred to as end panels and panels 210 and 214 as side panels because the former are illustrated shorter than the latter, but it is to be appreciated that the reverse may be true or that all of the outside panels may be of the same length.

As shown in FIGURE 1 each of the end panels 212 and 216 have attached to each of their end edges via a hinge or fold line, a respective flap. For example, end panel 212 has hinged thereto along the fold line 218 a flap 220, and at its other end along the fold line 222 there is hinged a flap 224. Likewise, end panel'216 has hinged to it at respective fold lines 226 and 228 the flaps 230 and 232.

The fold lines above mentioned may be of the cut and scored type as is conventional for allowing ease of folding along a given predetermined line. Additionally, fold lines 218 and 226 are either aligned with, or preferably parallel and slightly offset outwardly with respect to, the fold line 204 to compensate for the thickness of the sheet material in the succeeding folding operations, as is customary in the art. A similar sort of situation may exist as to fold lines 222 and 228 relative to the side fold line 200. Generally, an oifset 0r bending allowance, for example is desirable.

It will be noted from FIGURE 1 that each of the side panels 210 and 214 includes two cuts or internal slits respectively designated 234, 236, 238 and 240. Each of these slits has a triple directional characteristic, that is, each has a vertical element 242, a sloping element 244, and a horizontal element 246 the purpose of which will be more apparent from the later description of the carton setting up procedure.

Each end edge of each of the side panels 210 and 214 is uniquely formed with first and second portions 248 and 250 successively proceeding from the intersection 252 at dilferent angles.

Since each of the corners of the carton blank in FIG- URE l is the same as each other corner, reference is now made only to the upper left corner of FIGURE 1.

In the specific embodiment illustrated in FIGURE 1, the first portion 248 of the end edge of side panel 214 proceeds outwardly from intersection 252 substantially in line with the hinge line 202, i.e., at an angle of sub stantially relative to hinge line 204. It will be later apparent that this end edge portion 248 may extend outwardly from the intersection 252 also at either an acute or oblique angle relative to fold line 204, the main feature of the carton blank being that the second end edge portion 250 extends at an inwardly rotated acute angle, for example 12, relative to end portion 248. This angle may be considerably increased, or decreased to some extent, and the intersection 254 of these end portions may be moved up or down somewhat within the scope of this invention, though intersection 254 preferably falls on an imaginary line that is parallel to fold line 204 and spaced therefrom approximately midway to the outer edge of side panel 214.

Flap 220 includes a main body portion 256 and a tab 258 having a tip 260. The upper outer edge 262 of the tab is preferably horizontal while its sloping edge 264 makes an exemplary angle of 45 with the horizontal and vertical. The inner open edge 266 of flap 220 extends from intersection 252 preferably at an angle to the vertical, for example 12, but no limitation to such an angle is intended since the angle may be reduced to as Well as increased up to a value of about 30 for example.

Again as exemplary, the angle of portion 244 of slit 234 may be 42 relative to the horizontal, thi being preferably slightly less than the angle of tab edge 264 for better locking purposes, and the length of slit portion 246 may be such as to extend to the are centered on intersection 252 and which would intersect an extension of tab edges 262 and 264. Vertical slit element 242 extends closer to fold line 204 as the angle between flap edge 266 and vertical approaches 0.

The carton blank of FIGURE 1 may be erected into a box or container like that shown in FIGURE 2 by simple manipulation of the different foldable parts of the blank, along with a pivotal flexing or bending operation to cause the tab tip to completely enter the slit in the adjacent side panel, all as now fully described in detail.

Generally speaking, the making of the carton in FIG- URE 2 will normally start with the FIGURE 1 blank being in a substantially fiat position as illustrated. It is then necessary to start folding the different side panels upwardly about their respective fold lines 200, 202, 204 and 206, and to begin folding the end flaps 220, 224, 230 and 232 inwardly. In the specific example illustrated, adjacent side panels eventually com-e into a substantially right angle relationship with each other and the main or bottom panel 208, but it i to be realized that such a right angle relationship is not essential to this invention since the carton may have more or less than four corners, and since either the side panels 210, 214 or the end panels 212, 216 or both may make either an acute or oblique angle with the main panel 208 when in their erected and locked position, as desired.

In folding up the outside panels, side panels 210 and 214 are folded up before end panels 212 and 216, so that the flaps 220, 224, 230 and 232, which may be folded toward a right angle relationship with their respective end panels while that end panel is being folded up, may have their interior surface in substantially abutting relationship with the exterior surface of the respective end portion or part of the adjacent side panel 210, 214.

In the meantime, slit 234, 236, 238 and 240 are opened by relatively moving the portions of the side panels on either side of the slits in opposite directions, for example by moving the outer portion 268 outwardly without, but preferably with, concurrent movement of the interior pOrtion 270 inwardly. Then, as the end panels 212 and 216, with their respective pairs of flaps folded at substantially right angles with the end panels, come into a right angular relationship with main panel 208, the lower portion 272 of each end of each end panel 212 and 216 abuts the end edge 248 of the adjacent end portion of the respective side panel 210, 214. The end panels 212 and 216 can then be no further rotated about their respective hinge lines 202 and 206, since abutments 248 act as stops and prevent such further rotation of the end panels, and consequently of their pairs of flaps.

The right end corners of the carton in FIGURE 2 show the end and respective side panels completely locked, but for the moment attention is turned to the left end corners of FIGURE 2 since they both illustrate the situation as it exists at the present point of the setting up procedure. It will be noted that tabs 258 of flaps 220 and 224 are disposed out of overlapping relation with the respective cuts or slits 234 and 236, i.e., that tips 260 of those flaps are still on the exterior side of side panels 210 and 214 though large parts of tabs 258 are on the inside of those side panels.

For greater clarity, reference is made to FIGURE 3 to indicate the just explained condition as to the lower left corner of FIGURE 2. In particular, in FIGURE 3 it will be seen that the tab tip 260 extends above the horizontal portion 246 of slit 236, and consequently there is as yet no locking by the flap 224 since its tab 258 is not completely through the slit. At this stage in the procedure in the prior art, such as in the Meller patent above referred to, the tab tips are pulled through the slit manually by flexing the tabs sidewise appropriately. With the present invention, there is no need to bend or flex the tab at all, and therefore automatic machinery can cause the flap and side panel to be interlocked, in the manner now explained.

The intersection 254 of the lower stop portion 248 and the upper relieved portion 250 of the end edge at each end of each side panel, forms a respective fulcrum about which the adjacent end portion of each of the end panels 212, 216 may be inwardly flexed, bent, deflected, pivoted, or rotated, as you will, by pressure on the exterior surface of the upper part 274 against the natural bias of the end panel 212, 216, as shown in FIGURES 4 and 5. As apparent, this rotates the respective flap and its tab tip 260 inwardly toward the hinge line 200 or 204 between the adjacent side and main panels. Generally, the pressure or force causing such rotation is sufficient to make the upper part 274 abut the relieved end edge portion 250 of the side panel, but it is to be understood that such abutment per se is not essential though generally preferred, according to the angle of relief of portion 250 and the degree of locking security desired. The main point here is that the external pressure on part 274 causes tab tip 260 to rotate inwardly and downwardly sufliciently to come fully below the horizontal element 246 of the slit so that the tab 258 fully enters the slit. It then has its outside surface substantially abutting the inside surface of the inner end part 270 of the adjacent side panel end portion while the remainder of the flap has its inside surface substantially abutting the outside surface of the outer part 268 of the same side panel end portion,

For clarity, FIGURES 4 and 5 show the lower part 272 bowed convexly considerably due to the pivoting action about fulcrum 254, but such extreme bowing may tend to be somewhat of an exaggeration in reality. In any event the flexed configuration per se of this lower part is not important as far as this invention is concerned. What is important is that there be some return bias present due to the rotation inwardly, and such is present because the end panel end portions making up the lower and upper part 272, 274 at each corner are made of material which has suflicient resiliency to spring back to their original rectilinear shape. In fact, all of the blank is preferably made of such material, any material such as paperboard well known in the art for making cartons and the like.

Because of such resiliency in the end panel end portrons, upon release of the force causing the flaps to be rotated as in FIGURES 4 and 5, those end portions return to their upright position as required by the respective stops or abutments 248 at each corner. In so doing, the flap at each corner, as shown in FIGURE 6, interlocks securely with the slit thereat by the tab tip 260 staying on the inside of the side panel and extending above slit element 246 whereby the tab overlaps the slit with its inner edge 264 crossing the sloping slit element 244. With the flap in this locked position, it is positively locked therein by abutment 248 since no amount of inadvertent folding or the like of either end panel 212, 216 about its hinge with the main panel 208 can cause any unlocking of the secured corners. To effect an unlocking, a re-application of pressure to upper part 274 suflicient to rotate tip 260 below slit element 246 so it can slip back therethrough is required. Such force is not likely to be encountered in handling and use of a carton once it is initially set up.

Though it is preferable to have the tab and slit dimensioning such that there is substantially no play therebetween after the end panels return to rectilinear form and are in full abutment against lower end edge 248, but such is not an absolute requirement as long as the play is not so great as to allow any tab tip to become untucked thereby or by only slight pressure on upper portion 274. Additionally, as previously indicated, abutments 248 need not be at 90 to their respective fold lines 200 and 204, but may at any desired acute or oblique angle relative thereto, as long as the upper portion 251 is inwardly relieved from alignment with lower portion 248 by an angle preferably in the lower acute range such as the 12 above mentioned.

Intersection 254 forms a fulcrum as above indicated, and it also effects a stop of end panel rotation about its hinge as does abutment 248 as a whole. It is to be realized, however, that all is required is a stop and fulcrum, meaning that edge 248 could slope or meander inwardly from the stop-fulcrum point 254, if desired, though such is not preferable.

Even though FIGURE 1 and the discussion above have indicated the blank to be of the type in which opposite outside panels each have their two ends similar in configuration, it will be appreciated that the flap and slit arrangement at any corner of the blank may be reversed so that, for example end panel 212 would have a slit at one end for cooperation with a flap added to the end of side panel 210 but at its other end have the flap 220 as shown.

It will be appreciated from the foregoing that neither the tab 258 nor any other part of any end flap needs to be bent to get the tip 260 tucked into their respective slits, as the prior art requires. Because of the absence of this requirement and the presence of a simple force to execute the operation of pivoting the end panels about a fulcrum, the carton blanks of this invention may be set up not only manually but also automatically in accordance with the inventive method and apparatus set forth in my aforesaid divisional application.

Though this application has generally indicated that all sides of the carton are set up, it will be appreciated that such is not necessary, for in certain instances it may be desired to leave one, or perhaps more, outside panels unerected, while the others are erected, in order to allow bakery goods or the like to be slid into the carton.

It will thus be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiments of this invention have been shown and described only for the purpose of illustrating the principles of this invention and are subject to extensive change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

1. In a blank foldable to form a carton or the like having a plurality of corners, the area of the blank for one of said corners being formed by first and second outside panels and an inside panel to which said outside panels are hinged respectively along adjacent inside panel edges, said first outside panel having hinged to its end edge at said one corner a flap which defines a locking tab having a tip, said second panel having an internal slit adjacent its end edge at said one corner for receiving said locking tab, the improvement comprising fulcrum means at the said end edge of said second panel and including a fulcrum intermediate the outer edge of said second panel and the hinge of the second panel to said inside panel for initially preventing at least complete entry of said tip into said slit when said first panel is fully folded about its hinge with the said inside panel but then allowing complete entry of said tip into said slit when the so fully folded first panel is then flexed about the fulcrum to cause said tip to rotate toward said inside panel and through said slit.

2. A blank foldable to form a carton or the like comprising a main panel having a plurality of edges, a plurality of side panels respectively hinged to said edges for folding to erected position to form a plurality of carton corners, the corner areas of said blank respectively for said corners being formed by a respective set of adjacent side panel end portions one of which has hinged to its end edge a flap defining a locking tab having a tip, the other side panel end portion in each set having an internal slit formed and disposed from its end edge to receive said tab and effect locking together of the respective side panels, said other side panels including at their end edges a respective fulcrum means having a fulcrum intermediate the outer edge of the respective other side panel and the hinge thereof to said main panel for initially preventing at least complete entry of the adjacent tab tip into its respective slit when the respective said one side panel end portion is fully folded about its hinge with the said inside panel but then allowing complete entry when the so folded end portion is then flexed about the respective fulcrum to cause said tips to rotate toward said inside panel and through their respective slits.

3. A carton or the like made from the blank of claim 2 with said tips locked in said respective slits.

4. In a carton blank of the type including a main panel and a plurality of side panels hinge to the edges of said main panel for movement from a blanked position wherein said side panels are disposed in the plane of said mainpanel and an erected operative position wherein said side panels are disposed at an angle with respect to said main panel to form a container or cover, and in which at least one adjacent pair of end portions of adjacent side panels includes a flap defining a tab hinged to one of said pair of side panel end portions for movement from a blanked position wherein said flap is disposed in the plane of the associated side panel to a locked operative position wherein the interior surface of said flap is disposed in substantially abutting relation to the adjacent exterior surface of the other of said pair of side panel end portions, and a cut formed in said other side panel end portion for receiving said tab inwardly therethrough when said flap is disposed in said locked operative position, said out and tab being so related that when the associated side panels are disposed in said erected operative position said tab overlaps said cut in the locked operative position thereof so that said tab is prevented from movement out of said out without a deflection of at least a portion of the blank out of its operative position, the improvement comprising the end edge of said other side panel end portion including a stop portion having at least a fulcrum part removed from the hinge between said main and other side panel and being shaped and positioned to engage the interior surface of said one side panel end portion adjacent the hinged flap thereon and prevent a non-deflecting movement of said one side panel end portion into a position wherein said tab is disposed in the aforesaid overlapping locked relation with said cut, said end edge also including a relieved portion extending angularly outwardly from said stop portion and of a size and shape sufficient to permit said one end portion and flap to be flexed about said fulcrum part of the said stop portion as a fulcrum to thereby effect movement of said tab into said overlapping locked relation with said out by permitting complete entry of said tab through said cut.

5. A blank as in claim 4 wherein said stop portion and relieved portion of the said end edge of said other side panel end portion are respectively first and second substantially straight portions of the said end edge and are angularly displaced so that their intersection forms the aforesaid fulcrum.

6. A blank as in claim 5 wherein the said first portion extends at approximately 90 to the hinge between the said main panel and the said other side panel.

7. A blank as in claim wherein said intersection is on a line that is approximately halfway between the outer edge of said other side panel and its hinge with said main panel.

8. A blank as in claim 4 wherein the improvement further comprises said out being triple directional.

9. A sheet material blank foldable to form a carton or the like having a plurality of corners, the area of the blank for one of said corners being formed by first and second outside panels and an inside panel to which said outside panels are hinged respectively along adjacent inside panel edges which intersect at an angle corresponding to the angle of said one corner, said first outside panel having an end edge which ends substantially at the said intersection of said inside panel edges, said second outside panel being resilient at least at its end part adjacent said intersection and having hinged to the end edge of said part a flap which defines a locking tab having a tip, said end edge of said first panel forming in successive portions from said intersection respective first and second angularly displaced abutments for corresponding first and second portions of said resilient second panel end part, said first panel having an internal slit adjacent its said end edge for receiving said locking tab, when said second panel is folded about its hinge with the said inside panel to cause the said first portion of said resilient second panel end part to engage said first abutment, to the exclusion of said tab tip if at least the said second portion is not then substantially flexed toward said second abutment but to the inclusion of said tip if said second portion is so flexed and substantially engages said second abutment.

10. A foldable blank as in claim 14 wherein said first end edge abutment forms a substantially straight line proceeding from said intersection at an angle of approximately relative to the hinge line of said first and inside panels, said second abutment forming a substantially straight line disposed at an acute angle relative to the said hinge line.

11. A fol-dable blank as in claim 10 wherein the said intersection of said first and second abutments is on a line which is parallel spaced from said hinge line at approximately halfway between the outer edge of said first panel and the hinge line thereof with said inside panel.

References Cited by the Examiner UNITED STATES PATENTS 1,319,263 10/1919 Baker 22935 2,031,806 2/1936 Weiss 229-39 2,625,085 1/1953 Bergstein -55 2,637,252 5/1953 Swisher 95-55 2,967,654 1/1961 Palmer 22,9--35 3,059,829 10/1962 Thompson 22935 3,069,061 12/1962 Dion 22935 3,086,691 4/1963 Forbiano 22935 FRANKLIN T. GARRETT, Primary Examiner.

0 EARLE I. DRUMMOND, Examiner. 

1. IN A BLANK FOLDABLE TO FORM A CARTON OR THE LIKE HAVING A PLURALITY OF CORNERS, THE AREA OF THE BLANK FOR ONE OF SAID CORNERS BEING FORMED BY FIRST AND SECOND OUTSIDE PANELS AND AN INSIDE PANEL TO WHICH SAID OUTSIDE PANELS ARE HINGED RESPECTIVELY ALONG ADJACENT INSIDE PANEL EDGES, SAID FIRST OUTSIDE PANEL HAVING HINGED TO ITS END EDGE AT SAID ONE CORNER A FLAP AT SAID ONE CORNER FOR RECEIVING TAB HAVING A TIP, SAID SECOND PANEL HAVING AN INTERNAL SLIT ADJACENT ITS END EDGE AT SAID ONE CORNER FOR RECEIVING SAID LOCKING TAB, THE IMPROVEMENT COMPRISING FULCRUM MEANS AT THE SAID END EDGE OF SAID SECOND PANEL AND INCLUDING A FULCRUM INTERMEDIATE THE OUTER EDGE OF SAID SECOND PANEL AND THE HINGE OF THE SECOND PANEL TO SAID INSIDE PANEL FOR INITIALLY PREVENTING AT LEAST COMPLETE ENTRY OF SAID TIP INTO SAID SLIT WHEN SAID FIRST PANEL IS FULLY FOLDED ABOUT ITS HINGE WITH THE SAIE INSIDE PANEL BUT THEN ALLOWING COMPLETE ENTRY OF SAID TIP INTO SAID SLIT WHEN THE SO FULLY FOLDED FIRST PANEL IS THEN FLEXED ABOUT THE FULCRUM TO CAUSE SAID TIP TO ROTATE TOWARD SAID INSIDE PANEL AND THROUGH SAID SLIT. 